Mine skip



Nov. 17, 1953 c. ERICKSON 2,659,502

MINE SKIP Filed May 2, 1951 8 Sheets-Sheet l INVEN TOR. LEW/s C. BQ/C'KSON ll! an 1 L. C. ERICKSON Nov. 17, 1953 MINE SKIP 8 Sheets-Sheet 2 Filed May 2, 1951 INVENTOR. LEW/s C. EIQ/c so/v Nov. 17, 1953 c. ERICKSON MINE SKIP 8 Sheets-Sheet 5 Filed May 2, 1951 INVENTOR. LEW/5 C 'EQ/C'KSON M4 W L. C. ERICKSON Nov. 17, 1953 MINE SKIP 8 Sheets-Sheet 4 Filed May 2, 1951 INVENTOR. Laws C. EQ/OKSON Nov. 17, 1953 c. ERICKSON MINE SKIP 8 Sheets-Sheet 5 Filed May 2, 1951 J INVENTOR.

LEW/s EQ/OKSON BY W L. C. ERICKSON Nov. 17, 1953 MINE SKIP 8 Sheets-Sheet 6 Filed May 2, 1951 INVENTOR. LEW/s C. EQ/cKso/v Nov. 17, 1953 L. c. ERICKSON 0 MINE SKIP I Filed May 2, 1951 8 Sheets-Sheet '7 INVENTOR.

LE /5 C. EQ/CKSON ...v BY I 43 I /7 Fc.19 aw/4W Nov. 17, 1953 c. ERICKSUN ,50

MINE SKIP Filed May 2, 1951 8 Sheets-Sheet 8 INVENTOR. LEW/s CT EQ/C'KSON Patented Nov. 17, 1953 MINE SKIP Lewis 0. Erickson, Duluth, Minn., assignor to National Iron Company, Duluth, Minn., a corporation of Delaware Application May 2, 1951, Serial No. 224,226

6 Claims.

Thi invention relates to new and useful improvements in mine skips, generally, and particularly to a novel mechanism for automatically imparting a positive load-dumping action to the skip body when it reaches a predetermined location in its travel, as, for example, over a receiving hopper.

Various types of equipment have in the past been used for transporting material out of open pits or mines, including motorized trucks, and trains of dump cars, usually propelled by locomotives. The use of such equipment for removing strippings, ore, and other bulk materials from deeppits or mines is fast losing favor with many mine operators for various reasons, for example, because of the inability of such equipment to negotiate relatively steep inclines or grades, thereby requiring long, winding road-beds which comprise benches left around the pit walls, thus making less ore available for excavation from a given area, and also because of the continual expense incurred in the maintenance of adequate roadways and trackage for such rolling equipment. In addition, the cost of maintaining a fleet of vehicles, such as motorized trucks, and other equipment necessary in the operation thereof, usually runs extremely high. The use of other forms of material handling equipment have therefore been resorted to, such as cableoperated skips, but to the best of my knowledge from wide experience in the field, none of these have proven entirely satisfactory.

The present invention is directed to the latter type of apparatus, and preferably comprises two skip mounted for alternate up-and-down traveling movement between a loading station, which may be located at the bottom of an open pit or mine, and an unloading station, usually located exteriorly of the pit or mine.

An object of the present invention, therefore, is to provide an improved mine skip adapted for traveling movement between a loading point at the bottom of an open pit or mine, and an unloading station located at a higher elevation and laterally spaced from the loading point, usually exteriorly of the pit or mine, and means being provided at the unloading station for automatically imparting a positive load-dumping or rocking movement to the skip body upon its supporting chassis, whereby the load dumping movement of the skip body is progressive and constant throughout the cycle, including the return movement of the skip to load-receiving position, thereby greatly minimizing shocks and severe strains in the cables and other equipment, and

thus protecting them against damage from such shocks and vibration, even when handling material which may contain large heavy chunks or particles, which frequently have a damaging effect upon equipment when a load is suddenly dumped into a hopper or other receiving means.

A further object is to provide a skip comprising a uitable frame or chassis provided at its front and rear ends with suitable carrying wheels adapted for traveling movement upon suitable rails, a skip body pivotally carried by said frame, and a cam mechanism located at the upper end of the track adapted to be engaged by means carried on the skip body, thereby to impart a rocking motion to the skip body to dump its contents into a suitable receiving means when the skip reaches a predetermined position in its upward travel. v v

A further object is to provide an apparatus comprising a pair of skips each including a wheeled frame having a load-carrying body mounted thereon for pivotal movement about horizontal axes disposed transversely of the skip, and the forward ends of the wheeled frames of said skips being operatively connected to the ends of a pull-cable which has an operating connection with a power device, not shown in thedrawings, and which, when operated, will cause the skip to alternately move up and down on their respective supporting tracks between a skiploading station at the bottom of a pit, and a receiving station such as a hopper which may be located above the pit.

A further object is to provide an improved operating mechanism for a tiltable skip body, comprising a pair of cam plates located at opposite sides of the skip supporting rails at the point of material discharge, and each of said cam plates comprising a longitudinally extending cam groove adapted to receive a cam roller carried by the forward end of the skip body, said cams being fashioned to impart a uniform rocking motion to the skip body on its supporting chassis as the skip approaches a position over the receiving hopper, and whereby the rockin or load-dumping motion imparted to the skip body is progressive and uniform throughout its travel, when dumping its load, and when returning to loadreceiving position, whereby the dumping of the load into the receiving hopper may be accurately controlled, regardless of the nature of the material being handled, and regardless of the location of the center of gravity of the load.

A further object resides in the novel construction of the skip, per se, which includes a supporting frame or chassis provided at its forward end with suitable guides for movably and resiliently supporting a pair of journals which rotatably support an axle having a pair of flanged wheels secured thereto for traveling movement upon suitable rails, and a rocker or evener being pivotally mounted in the rear end of the supporting frame of the-skip adapted'forirocking movement about an axis disposed lengthwise of said frame, the opposed ends of said rocker engaging a pair of spring elements having their lower ends seated on journals mounted for vertical movement in suitable guides provided in the rear end portion of the skip frame, -and!an axle being mounted in said reart-journals'iandmaving similar flanged wheels secured thereto, said rocker cooperating with the carrying wheels atrthe front end of the frame to provide a three-point suspension ior the skip frame on its supporting rails, and the resilient mounting of the axle supporting journals functioning to assist inrabsorbing load shocks.- and. cooperating iwith .-.t-he evener to -compensatet foriirregularities rinzthe. rails ,of theitrack .overmwhichi the skip travels.

Other objects of the inventionreside inathe unique .mountingaand construction ,ofthe load- .carrying body of the ,skip; the walls qof --which Imay besgof box-like cross-section, i, whereby. they imaysbe r made of 41301161 ,plate intimately welded ttogetherato; provide, ginqeffect, -an.-integralstr-uc turehavinggreat strength-and. ruggedness, with :aominimumeof weighaaand whereby said a walls provider-a .certain ,degree of resiliency which co- .operates with the spring mounting of the skip body; ,upon its supporting:chassisto. absorb. severe load impactsandsshocks inzthe. unique. constructionot the bottom-wall:oithaskipbody whereby a plurality of closely spaced ducts are provided ,therebeneath through vw-hichtaisuitable heating mediumamaydae circulated, ifadesired,r-to permit operation of-; the apparatus -.in';freezing temperatures; :in the ..-novel.constructionof the :ca-ble attaching/means for;detachably'securingtheends f ithe pull-cables .to:.the Wheeledyfra-mes'ofithe skips, whereby the \cable sends may Lreadily :and quickly he'secu-red thereto without :damaging; the .cable, andtalso'twherebycable slack may readily "be taken up =.in-- a! comparatively -,short 1511310930]? time, if necessary, and" whereb .the-,:ends, of 1: the pull-cablesare-attachedz to .theinrespective--skips atamelevation close togthe rails;v thereby. termini- .mize whip =i-n,;the cables; and also Wherebyshould the operating mechanism for;the pullacablestfail whenravski-p reaches .-its.,-load-;dumpi-n g position,

.the .sk ip :may pass :completelyiover .theirhead :shcaves withoutiseriously damagingisaid sheaves orthesupporting: structure.

A' further 7 object of :my--. invention-is to provide, :asaarsafetyfactonfmeansfto lock the :skip :body its' load=carrying position @during :its loading v andload-carryingperiods, and to unlock same =immediately'before the dumping operation'begins.

These and other objects of'the invention and the means for their attainment will be more apparentjrom the following .description taken in connection .with the accompanying drawin s.

'gIn theaccompanyingidrawingsv there has been disclosed a structure designedto .carry out the various objects ,of the. invention, but it is ,to be understood that the invention .is notv confined, to the exact features.shown,..as .various changes may be. made within the scope ,of-ttheclaims which follow.

In the drawings:

Figure 1 is a diagrammatic view illustrating a typical installation such as utilized in open pit mines, wherein one of the skips is shown in loadreceiving position at the bottom of the pit, while the other skip is in load-dumping position above the pit;

Figure 2. is a view showingzga loaded-zskip approaching the unloadingstation above the ground level;

iFigure 3 is a view partl in section showing the. cam rollers on the skip body entering the cam grooves of the skip body operating mechanism;

Fig-urea is a view. similar to Figure 3, but show- .:ingthe:body;of the skip partially tilted to load :dumping'position;

Figure 5 ,is-a view similar to Figure 4 showing in'full lines the skip body in its full load-dumpingrzposition;

Figure 6 is an enlarged detail sectional view .onzthelineafifi ofeF-igure 8,:showing oneof' the .cam engaging rollers "on the 1- skipbodyengaged ina: cam igroove;

:Figure "7 is an enlarged. detail; sectional view on the.- line 1-4 of Figure 9, showing one of the control teams of the skip .tengaged with its: respective guide roller;

Figure 8 1 is a. fragmentary view showingin'full lines the position of. one: of: the .cam rollers when the skip body-initially beginsits tilting. orload- .dum-pi-ng 'movement and:showing in dotted-lines the position ,of the cam. roller ion the a skip when entering; the depression or gap in-v thembottom. of the cam-plate, .with the ,tniangulan ;camvelement i thereof about to enter the upwardly and ,for-

warmly-extendin portion-zoftthe. cam-. groove;

vFigure ,9 his ;a view similar ,to ,l-Figure 8, .but showing ,the. .ca1n-.- roller ,of .the skip 1 inttheypost tion assumed when a the skip approaches; its full dumping position, illustrated Figure; 5;

FigurelO is :azdiagrammatic-view. illustratingin full and dotted dines-various positions assumed by .the skip carz-during itsz-load-idumping -movement;

Figure=11 :is an; enlarged detail sectional view substantially: onrthe, line I -|--l I: of" Figure 15;

..Figu-re 12'.is:a.detailsectional viewton therline -l2-|'2- .0f Figure :11;

:Figure l3t-is an enlarged detailzsectionalvview on theline l-3.l3;hof Figurelll;

.tEigur-e 1.4 is av diagrammatic planview showing the preferred arrangement :.of.:the two sets of tracks :adiacent :to the'zun'loa'ding :station, and

:alsoshowingthe, location-of the cam plates relative: to :the rails :of 'the tracks;

' Figure" 15 is an enlarged plan view of askip with its load-dumping body in normal loadcarrying position;

Figure 16 is a rear end view ;ofia skip-with its load-carrying body in the position :shown in Figure 15;

Figure 17 is .a'longitudinal sectional viewon the line ll-l? of'Figure 19,showing the ,box-

like construction ;of thewa'lls of the skip-body;

Figure ,18 is aside elevation of 1 Figureil'i;

Figure 19 is ,a cross-sectional view ;on ,theline [9-19 .of Figure l8,*sh0wing vthe 'trunnions at the Opposite ,sides ,-of-;theskip body;

-Figure,20 is a bottom-view;offiFigure l8; and

Figure 21 issarrear view:of;the:skipi'body.

Loading station and unloadingstation In the selected embodiment of the invention .hereindisclosed,..the1'e is diagrammatically -,-il-

lustrated in Figure 1 a mine skip installation comprising a pair of inclined tracks 2 which extend downwardly into an open pit or mine 3 to a loading platform 4, onto which a conventional dump truck 5 may be driven to dump its load into a skip 6, shown positioned adjacent thereto. The loading platform 4 is of simple inexpensive construction, whereby it may readily be moved as the loading point follows operations to deeper levels. The tracks 2 continue upwardly above the ground level and are herein shown terminating in a head frame 1, which supports the operating mechanisms for actuating the skips, including supporting sheaves 8 which have running connections with the pull-cables of the two skips. The power means for operating the cables is of conventional construction, and therefore need not be illustrated in the drawings.

An important feature of the invention resides in the relationship between the upper ends of the rails 2 and the sheaves 8, whereby should one of the skips accidentally excessively overrun its unloading position, shown in full lines in Figure 1, it could, without causing serious damage to the sheaves 8 and the control tower, pass completely over the sheaves 8 onto the ground below the tower. Such an incident could rarely occur because the trackage is extended a considerable distance beyond the receiving station 62 to take care of most abnormal over-runs, as illustrated in Figure 1.

Skip and supporting chassis Another important feature of the invention resides in the specific construction of the skip which, as best illustrated in Figures 2 to 4, inclusive, and and 16, comprises a load-carrying body 9 having oppositely disposed trunnions I0 secured thereto and mounted for rocking or tilting movement in suitable bearings or journals ll provided on the side beams or members of a carrying frame or chassis I2, whereby the skip body 9 is mounted for pivotal movement on an axis disposed transversely of the chassis I2, as will be understood by reference to the drawings. Journals I I are provided with split sleeves or bushings 49, the lower halves of which are spherical in configuration whereby when supported in the journal boxes H, shown in Figures 2 and 3, the bushings are made self-aligning to compensate for variations or irregularities in the mounting of the body on the chassis frame, and also whereby any mis-alignment or distortion of the chassis frame will have no effect upon the pivotal action of the skip body thereon. The upper faces of journal boxes I I are preferably disposed at an angle to the upper edges of the side members of the chassis frame, and are open to form saddle-like supports adapted to detachably receive the split bushings 49 which rotatably support the skip trunnions ill in the journal boxes II. By this arrangement, should the skip body accidentally become damaged, another one may readily be substituted therefor by simply lifting the damaged skip body from its supporting chassis with a suitable crane.

The frame or chassis l2 comprisesfront and rear cross members i3 and M, respectively, and side members l5, all of which are shown con- 'structed of high-tensile steel plate, whereby said frame members are box-shaped in construction, cross-sectionally, thereby to provide the utmost in strength and ruggedness with minimum weight. Light weight is an important factor in an apparatus of this general type, as it makes it possible to relatively increase the pay load carried on the skips.

The forward end of chassis i2 is provided at each side with vertically disposed guides 16 adapted to slidably receive a pair of journal blocks 11 which rotatably carry an axle l8 to which are secured a pair of flanged wheels l9 adapted to travel on the rails 2| of the tracks 2, as will be understood by reference to Figures 2, 3, 15 and 16. Suitable means not shown is provided for retaining the journals H in the guides H5. Spring elements 22 are shown interposed between the upper ends of journals I! and the bottoms of the inverted guides IE to resiliently support the forward end of the chassis frame upon the front axle 18, as will be under stood.

Three point suspension Another important feature of the invention resides in the means provided at the rear end portion of the chassis frame to provide a threepoint suspension for the chassis frame on its supporting wheels. Such means is shown comprising a rocker or evener 23, mounted for rocking movement upon 'a pivot pin 24 preferably having its ends fixed in the walls of the rear cross member 14 of the chassis. The opposed ends of the rocker 23 are received in the bottoms of vertical guides 25 provided at the rear corners of the chassis frame, and engage the upper ends of suitable spring elements 26, similar to springs 22 at the forward end of the frame. The lower ends of springs 26 are seated on the upper ends of a pair of journal blocks 21, movably supported in the guides 25, and which cooperate to rotatably support a rear axle 28 in a manner similar to the journal blocks ll at the forward end of the chassis, as will be understood by reference to Figure 16.

The above construction, as hereinbefore stated, is important in that the rocker cooperates with the front wheels to provide a three-point suspension for the chassis frame on its supporting wheels, whereby irregularities or variations in the rails 21 will not have any ill effects upon the operation of the skips as they travel back and. forth on the rails 2l of the tracks 2. The pro vision of the spring elements 22 and 26 at the front and rear of the chassis is also extremely important in that they sufficiently cushion the impact of loads dumped into the skip body at the loading station to greatly minimize damage to the skips.

In a skip installation such as herein disclosed, each skip is usually designed to carry a load which, in actual practice, is substantially equal to the load of a truck body, whereby an entire truck load may be dumped into an empty skip body stationed at the loading station, as shown in Figure 1. Such dumping of the material into the skip body results in extremely heavy load impacts on the skip which, in the present instance, the spring elements 22 and 26 of the skip chassis assist in absorbing. The severe load impacts imposed on the skips when being loaded, will be more fully realized when it is understood that the tail end of a loaded truck stationed on the loading platform in the bottom of the pit may be between fifteen and twenty or more feet above the bottom of the empty skip body, and the skips herein disclosed have theretofore been carefully designed and constructed to readily withstand such severe load impacts over long periods without damage.

Another feature. of the. invention, therefore, resides in the-novelconstruction of theskip body, per so, which, as best shown in: Figures 17- to 21, inclusive, is constructed entirely of metal, such as high-tensile steel plate, welded together to fOIIILbOX-likfi side walls, the outerwalls 29 thereof being here shown as having openings 33 therein to provide means whereby the vertical and. horizontal members 3t which space the inner wallsv 32 from thewalls'2 9 may be securely welded in place to form the box-like double wall construction here shown. The rear wall of the skip body issimilarly constructed to provide an outer wall 34 having, openings 36 and 3! therein and similar members 3| welded between the wall 34 and the inner wall 35. The box-like, double wall construction of the skip body provides for extreme strength because of the intimately welded association of the inner and outer walls with the spacer members 3I-3i secured between same at. substantially right angles to provide a plurality of adjacent relatively small box elements which provide great strength and reinforcement with-least possible weight.

The bottom M of the skip body is similarly of box-like construction, as, best illustratedv in Figure 19, and comprises, inner and outer plate elements 42 and 43. spaced apart by upright metallic. spacer and strengthening elements 44, all of which are intimately welded together to provide the. required strength in the same manner as the side and rear walls.

The skip. body is alsoprovided with strength and reinforcement its general construction; that is, the skipbody is so formed as to. have substantially U-shaped yokes tosupport and sustain its, loads and. stresses. These yokes are clearly illustrated in, Figures and 19. In Figure 15, it, can be. readily seen that the. skip body is open. in front, as at 39, and has. a U-shaped side and rear wall contour, with the trunnion t9 extending from the-yokessidewalls iii-29. This longitudinal yoke embraces the load of the skip body as the cables pull the skip. upwardly, of

course.

In. addition, there is a yoketransversely of the skip. body. .As seen. in Figure 19,. the cross section of the skip is of U.-shape and. the trunnions Ill are. secured to the side Walls 29-29. thereof whereby the, weight. of the load is. adequately supported between the trunnions I 0.

An abutment member 38 is provided on the rear wall 34 of. the skip and is adapted to. engage the upper surface of the rear cross member of the chassis frame when the skip body is in its normal load-carrying position, as seen in Figure. 2, to support the rear end of the skip body and prevent. its being tipped rearwardly on. its. pivotal mountings ID. The position of the. trunnions I-B relative to. the skip body is preferably slightly forwardly of the normal center of gravity of the skip body, both when loaded and empty. This positioning of the trunnions is to insure that the skip body is biased rearwardly and remains in its normal load-carrying position during its op eration except when it is intentionally caused to be tipped at the unloading station, as will become apparent. It is deemed apparent that the load of the skip body is supported between the trunnions |0l-8 and the abutment member 38 which rests on the rear transverse frame member, and that these parts, and their relation to each other, serve as means to hold the skip body against pivotal movement when traveling, especially when carrying a load, thus preventing loss 8. of material at undesired points along the skiptravel-path.

A wear plate 45 constitutes the effective bottom surface of the skipbody, and is shown supported upon a plurality of inverted angle irons 46, whereby a plurality of closely spaced fluid-circulating passages 41 are provided in the bottom wall of the skip body. The angle irons are disposed adjacent each other lengthwise of the skip body, as shownv in Figure 19. Should it be found necessary to operate the apparatus in freezing temperatures, a heating medium may be circulated through the passages-41 in the skip bottom, and, of course, the heating medium may be directed into the spaces between the side and back walls as well to keep material from stocking or freezing to the inner walls of the body.

A guard plate 52' is provided at the front end of the chassis frame, as best shown in Figure 4, and provides a partial front wall for the skip body when the latter is in its normal load-carrying position, shown in Figures 2 and 3. The guard plate 52 also extends forwardly and upwardly over the front cross member 13 of the chassis frame to prevent material from spilling forwardly into contact with the cable attaching means.

Cable attaching means Another important feature resides in the means provided for attaching the ends of the pull cable 20 to the chassis frames of the two skip cars, it being understood that the twoskip. cars are preferably utilized in the installation which are so arranged that when a loaded skip is ascending from the mine pit, an empty skip is descending to the loading station to receive another load.

The cable-attaching means is best illustrated in Figures 10 to 13, inclusive, and comprises a semi-circular member 53 having a peripheral groove 54 for receiving the pull-cable 20. The free end portion of the cable'is wrapped around a wedge-like element 55, indicated in dotted lines in' Figure 11, with the bight in the cable around the larger end of the member 55 and facing the direction of pull on the cable. Said wedge-like element with the cable thus wrapped about it is then inserted into a socket member 56 provided on the upper'portion of member 53, as shown at 51, the socket member being disposed above the member 53 and preferably forwardly of the vertically center line of the member 53. The angles of the opposed sides of wedge element 55 are such that when said element is forced into the socket member 56, as shown in Figure 12, and the cable 20 is placed under tension, a force is constantly exerted on the wedge element 55 to firmly secure it' and the cable in the socket member 56 without damaging the cable, and positively preventing'the cable from accidentally becoming detached from the skip chassis.

The cable-attaching means includes. the upright semi-circular member 53 which is a flat plate-like piece having its cable receiving, peripheral groove therein, as shown, and the socket member 56 attached thereto, as by welding, for example. The member 53 is removably secured to the front end of the skip frame, whereby the member 53, may be very conveniently removed and mounted on the cable with. comparative ease once the mounting point has been established, as there will be no, difficult maneuvering of the unwieldy cable through slots or other small openings in confined. spaces. It is desirable that a cable clamp, suggested at 89, be installed adjacent the lower end. of the cable anchor plate 53,

9 as shown, to hold the cable securely in its mounting. With the plate 53 thus mounted on the cable, the plate and cable can be conveniently remounted on the skip frame, as shown.

The member 53 is secured to the frame of the skip by means of angle brackets 58 adjacent the upper end thereof, which are welded to the opposed vertical faces of the member 53, the brackets being bolted to the outer face of the downwardly projecting portion of the frame member I3, as seen in Figure 11, it being noted that the said outer portion of the member I3 is amply supported and braced by brackets 90 to carry the member 53. In addition, the member 53 is fastened to the transversely disposed anchor tie plate 9| as by angle members 92 disposed on each side of the member 53, the tie plate having a slot 91 therein to receive the member 53 and the members 92 being, preferably, welded to the tie plate on each side of the slot and having bolts 93 extending through the upwardly facing flange of the members 92 and the plate 53, as shown, whereby the cable anchorage is secure.

The tie plate 9| has an upwardly turned flange 94 on its outer edge, as shown, and has its inner edge welded to the lower edge of the skip body closure portion 52 of the member I3, whereby the tie plate has a girder effect and reinforces the frame of the skip as well as serving as a portion of the cable anchorage. Obviously, the cutting of the slot 91 into the plate 9| weakens same; however, I have provided a heavy bar of metal 98 to extend across the slot and to be bolted to the flange 94 of the tie plate on each side of the slot, thereby restoring the girder effect of the tie plate and further securing the cable anchorage.

To further provide adequate cable anchorage and to distribute the pulling stress as equally as possible to the skip frame, one end of a girder or stress distributing member 96 is firmly fixed to each end of the portion 52 of the member I3 adjacent the lower end thereof where the plate 9| meets the member I3. The opposite end of each of the girders 96 is secured to the side members I5 of the skip frame, preferably adjacent the trunnions I0, as shown in Figure 15. Thus it may be seen that there is a U-shaped yoke (girders 96-96 and tie plate 9|), which carries the cable pull on the skip, making for more even distribution of stresses.

By attaching the cable to the chassis frame as above described, and as shown in the drawings, the cable is located close to the surface plane of rails 2I, whereby whipping of the cable is reduced to a minimum. Such construction also makes it possible to readily vary the length of the cable at any time if necessary and also whereby excessive slack which may develop in the cable may readily be taken up without damaging the cable. If desired, the excess cable 59 may be supported upon the upper front frame member I3 beneath the forwardly extending guard member 52, said frame member I3 serving as a deck upon which to place the excess cable.

Skip body operating mechanism Another important feature of the present invention resides in the novel means provided for operating or tilting the skip body from its normal load-carrying position, shown in Figure 2, to its full load-dumping position, indicated at A in Figure 10, and back to its horizontal load-carrying position, indicated at B. This operation is extremely important in the operation of the skip body, as it assures a smooth rocking motion without any abrupt changes of direction, and the unloading of the material may be targeted to a restricted area, such as the wall (SI of the receiving hopper 52 in the control tower. Such controlled discharging of the load from the skip is accomplished regardless of skip speed, and minimizes spilling of material from the skip and damage to the equipment.

Cam plates The operating mechanism is best illustrated in Figures 2 to 9, inclusive, and comprises a pair of cam plates G3, shown secured to supporting beams 89 which may constitute a portion of the supporting structure of the receiving station, as shown in Figure l. The beams also provide the main support for the upper ends of the tracks 2 and the operating mechanism for the skips.

In Figure 14 is will be noted the installation herein disclosed comprises two tracks 2-2. The cam plates 53 are best illustrated in Figure 5. Two such cam plates are utilized for each skip, and are located adjacent to each pair of rails 2i, at the inner sides thereof, as clearly illustrated in Figures 14 and 15. Each cam plate 53 has a longitudinally extending cam groove 95, which may be formed by welding to one side surface of the plate a pair of spaced bars 65 and 9?, which extend forwardly and downwardly to a recess or gap 68.

Similar cam bars 69 and II are secured to the other end portion of each cam plate 63 and cooperate with the bars 66 and 6'! to complete the formation of the longitudinal cam groove 65, as will be understood by reference to Figure 5. The adjacent faces of cam bars 66 and 61 and cam bars 69 and II are provided with high carbon steel facings 12 which cooperate to provide wearing surfaces for a pair of cam rollers 13, mounted on brackets 14 secured to depending portions or structural brackets 15 provided at the lower front corners of each skip car, as best illustrated in Figures 3, 5, 17, 18, and 21.

The cam grooves and rollers 13 of the skips constitute a very important feature of the present invention in that this mechanism positively controls the dumping actions of the skip bodies, as each skip passes over the receiving, hopper BI. As hereinbefore stated, the dumping movement of each skip body is progressive and gradual from the time the skip body initiates it dumping movement until it has completely discharged its load and is returned to its normal load-receiving position, preparatory to returning to the pit for reloading. Such movement is important because it assures a gradual discharge of the material from the skip body as it is tilted to its full dumping position, clearly indicated in Figures 1 and 10, which greatly minimizes shocks and vibration.

The positive but gradual dumping or tilting action of the skip body is, of course, controlled by the relative formation or contour of the cam groove 65 with respect to the line of travel of the trunnions II], and the location of the cam or dump rollers 13 with respect to the trunnions. By referring to Figure 10 of the drawing, it will be seen that the gradual dumping of the skip body results because of the progressively varying distances between the cam grooves and the line of travel aa of the skip trunnions I0, it being understood that the distance between the skip trunnions I0 and the cam rollers 13 always I l remains constant. increment of travel of the skip body, the degree of tilt or dump of the skip body can be accurately predetermined and controlled by the formation of the cam grooves. In the instant disclosure, the initial tilt per increment of travel is butslight so that there will be least possible stress to the cable and other mechanism required to overcome the inherent inertia of the skip body which resists tilting. Once this inertia is overcome, however, the degree of tilt per increment of travel may be gradually increased-without undue stresses to the equipment.

In the same manner, the dumping of the skip can be targeted to a particular point of discharge irrespective of which of the said increments of travel the skip happens to be in at a given time. This is a verydesirable feature, as different types of material handled by the skips dump-s in different manners; in other words, some leaves the skip body relatively earlier than others, yet all materials engage substantially the same target point in the hopper 62. This makes it possible to design receiving stations in a manner to sustain the load-dumping shocks most efficiently, of course.

Because the skip frame travels ina continuously straight line, and only the skip body tilts, the cam grooves cannot, of course, be designed to; extend farther from the trunnions than thecam rollers-13 extend. Therefore, I have provided means for making it possible to use relatively flat-cam grooves to tilt the skip body more than 90, as shown, to insure complete emptying of theskip each time it is dumped. This means includes-V-shaped cam elements 16 fixed tothe roller supporting brackets 14 inwardlyof the cam rollers 13, the elements 16 being adapted to engage a pair of rollers 11, rotatably mounted on trunnions 18- of a pair of brackets 19, shown secured to the camplates'63 at a point intermediate the cam bars 66 and 69. See Figures 6 and '7. The rollers 11 are spaced inwardly from the cam plates 63, and are aligned with the cam elements 16 of the skip body so that said cam elements engage the rollers 11 when the cam rollers 13 approach the downwardlyopen gap 68in the bottom of the cam grooves between the cam-barsfi'l and I l, as shown in Figure, 3.

As isdeemed apparent from the drawings, especially Figures 7-, 8, and 9, the v-shaped cam elements take over fromthe cam rollers 13. as the. latter-move into the point where cam bars 66 and 69 meet; that is, the upper side of the cam elements 16 engageth'e rollers'lI-i and guide the cam'rollers'13 downwardly into the. gap 68 and the said upper sideof the cam passes beyond the. roller, as. shown, as the skip. moves forward. A's-the skip continues forward, the front corners of 'the skip are restrained from forward move ment momentarily until the trunnions lovpass over the center of the gap 61 to-the position shown at G: in Figures Band 10; As the skip frame. continues forward, the skipv body moves therewith, of-course, causing-therollers13 and cam elements 16: to. moveupwardly out of the gap 68.- Now, because of the V-shape ofthe cam elements. 16; the: other side thereof engages therrollers TI and they guide the dump or cam rollers 13 into thecam. groovearea E defined by the bars Hand 1 l and the skip body moves into thepositionD, as.- shown, until. the skip, reaches itsqfullload-dumping position A, attained when the-cam rollers 'I3:enter the straightportions Therefore, for each forward Fiof the.- cam grooves Gf-:- course, this action takes place relatively. fast and' ther-travel-of the.

skip-frame and body is uniformly-smooth so'that no jarring or.jolting-takesplaca This cam-dumping. arrangement, as-describ'ed, serves to make: the.- dumping-operation less -.criti: calin speed of dump and. insthelufinalgstopping place of the skip when. dumped, whereby; cable length does. not ;have.-to;be.- critically adjustedzto permit loading of the;-down:skip.

afe y. lqtchi l secur n s mb du i load-,carryingippsitjon As; a et actor me smoi d a i 9 nehe kin: d a nst il g r; meltin ment pni s r nn on vd r e he rav l n movement thereof between ;t l1 e; receivingl station n t e t m he it har br r ntenr. o i i i fv h i zz r iltin oliwer lr and interrupting its travel should. the center, of gravity; of; its. load;- be located forwardly of; its trunnions [0,: Because of; the-constructionhere tofore described, thisisnotlikelyto occur; how.- ever,in the construction and operation .of heavy equipment, it good practice to include-safety features. To lock; the skinbpdy againsttilting movement, a; pair of latches, generally desig; nated byuthenumeralfll, are'pivotally mounted on therforwardend of-thechassis frame} as shown at aain Figur s 2,3. 4 and 15.

h. a qhis ro i ed-at. it lw er. nd h a, pin 83 adaptedtoengage; Scatter notches-,8! provided; in the lower ends. of arpair, of; latch; engaging, members 85.-secure 4:l to, the. forward end or the-skipbody inrlaterally. spaced, relation, as clearly illustratedinFiguresBmnd. 15; 1301-. lers 86 are also mounted on the lower endssof the latch armsgand; arerlaterallyofiset-in ,an outwarddirection from ltheiupper rollers; asillus: trated in Figu1: e 15. Rollers 8 5,, are, adapted, to engage stationary cambars 8hdisposed inspaced parallel relation; tofthe rails. ,zl, r t ack, 2,.whe the, skip; approaches its; loadsdumping position in the; control towen: Cam bars-81 extend, from the. lower ends. of thacam-plates 63 ,to, a,-,point well beyond the upper. endsof, the -.camplates; whereby the latches areretained inunlatching position throughout the. full dum ing travel. of theskipt In other words, latcl-r.memberm8,1 ma be actuated to release the skip. body; for. its JCS-d1 dumping. operation at or about the. time. the. cam rollers 13015. the. skip bodyenter the cam grooves 65, as shown in Figure .3, The, cam,,grooves are slightly outwardly flaredat. their lower ends .to permitfree. entryI thereinto; of the cam. rollers 13. when, the. skip-approaches, its load-dumping position, Assoonas. cam rollersfli-have. fully enteredncam grooves, 65, the cam grooves. take over-complete control. ofthe: dumping action of the, skip. body and, provide a positive. action whereby. theskip, body. rogressively tilted in a, forward direction. from: itsload-carrying position, shownuinFi llre 2, to its full load-dumping position, hqwn,in.full lines inEigure- 1, assisted; as stated, by the V-shaped cam elements 16,and rollers 11. The return movement of the skip body fromthe full lines position, shown in Figure 1,. to itsrload-receivings position, is controlled by the cams in amanner similar to the action imparted thereto when dumping its load;

In Figure 14, it will'be noted that only three latcheoperatingv earns: 81- are utilized, whereas each skip car;comprises twolatches. The-center latch; cam 1 8?!" thus servessthe; two skips, and to avoid interference between the adjacent latches of the two skips, the tracks 2 gradually diverge from the receiving station in an outward direction sufficiently to permit ample clearance between the two skip bodies at the point in their travel where they pass each other in their up and down movements on the tracks 2. The converging of the tracks at the receiving station permits the receiving station to be of less width, and obviously, reduces the bulk and cost of the receiving station proportionately.

Operation In the operation of the novel skip car installation herein disclosed, the skips, after having been operatively secured to the pull cable 29-, may be set into motion by an hoist operator located in any convenient location. The operators station, however, is preferably, and may Well be, arranged so that the operator may clearly view the loading operation at the bottom of the pit and the unloading operation in the tower. A suitable communication system may be provided between the operator in his control station, not shown, and the observer at the loading station, whereby the loading observer may signal or apprize the control operator each time a skip has been loaded and is ready to ascend to the receiving station. The apparatus is then set into motion whereby the loaded skip ascends to the unloading station, over the hopper 5 l, and simultaneously the empty skip descends to the loading station.

When the loaded skip approaches the control mechanism over the hopper 5|, the cam rollers '13 of the skip enter the cam grooves 65 at C in Figure 10, and simultaneously or immediately thereafter the latch rollers 86 engage the inclined surfaces 88 of the fixed cams 87, whereby the upper rollers 83 of the latches are moved out of locking engagement with the elements 85 to thereby release the skip body so that it may proceed with its load-dumping movement. As the skip passes between cam plates 53, its cam rollers 13 enter and follow said cam grooves. The V-shaped cam elements '16 prevent cam rollers '13 from passing over cam recesses 58 and into the lower portion E of the upper portions of cam grooves 63 before the skip is properly tilted, because the upper surface of the cam elements remain in engagement with the peripheries of rollers ll until rollers 13 have entered cam recesses or gaps 68, as will be understood by reference to Figure 4. As the advancing skip body tilts from position G to position D in Figure 10, the opposite face of the V-cams engages the rollers H to guide the cam rollers i3 upwardly into cam section E, is indicated.

This action, as hereinbefore stated, is extreme- 1y important in that it imparts to each skip car a positive dumping action which is gradual and uniform throughout its full cycle, and is not dependent upon nor can it be affected by gravity. The cam mechanism also compensates for any variation in the distance between the path of travel aa. of the skip trunnions ill and the supporting rails 2| of the tracks 2 as a result of the resilient mounting of the skip body upon its supporting chassis. In actual practice, the novel cam mechanism herein disclosed has been found to function positively and eiiiciently, and with the assurance that each load as it is gradually discharged from a skip body is directed onto a predetermined area substantially without shock to the skip mechanism, which is an extremely important factor in apparatus of this general type 14 where the load particles may greatly vary in size and weight.

The unique mounting of the skip body on its supporting chassis is also important in that it makes it possible to quickly remove a damaged skip body from its supporting chassis and substitute another therefor without requiring the removal of any bolts or other fastening elements.

Apparatus of this general type is usually subjected to extremely rough treatment because of the nature of the material to be handled thereby. It frequently contains large, heavy chunks which may be extremely heavy, whereby they may con tact the skip bottoms with severe impacts when dumped thereinto at the loading station. The particular construction of the skip body, the resilient mounting of the skip bodies upon their supporting chassis, and the inclination at which the skip is normally carried when loading and running protect the skips against damage from such severe load shocks. The three-point suspension of the chassis upon the rails is also instrumental in minimizing excessive strains which may be imparted to the skips as a result of irregularities in the rails.

It is to be noted that one of the features of my invention is that it is designed for use in open pit mining wherein the tracks lie on the wall of the pit, the walls of the pit, of course, being at an inclination which the material being mined in herently maintains. That is, the walls of the pit assume the natural angle of repose of the material being mined and the tracks are laid at this inclination.

The upper edge of the skip body and the skip bottom lie substantially parallel with the track, as is readily apparent from the drawings; thereby, when the skip is loaded from a truck or the like, the material assumes its natural angle of repose and the skip cannot be overloaded to the point that spillage will occur along the track as the skips ascend, as all spillage will occur at the loading station. In this manner also, the skip load can be accurately predetermined, and

,. it cannot be overloaded to put excess strains on the equipment, thereby providing for longer life and durability of the entire assembly.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

Having thus described my invention, what I claim is:

1. A skip installation for use in an open pit mine comprising, a track mounted on the walls of said pit at substantially the same inclination as said walls, a wheeled frame adapted for traveling movement on said inclined track between a loading station and an unloading station, a load carrying body mounted for pivotal movement on said wheeled frame, means for propelling the loaded skip from the loading to the unloading station, a longitudinally extending cam groove at the unloading station, said groove being divided into two shallowly curved segments which have their lowest extremities at the division point between said segments, a guide roller mounted intermediate said segments in laterally spaced relation to said groove, 2. skip roller mounted on the forward end of the skip body and engageable with said cam to gradually tilt the skip body on said wheeled frame to its maximum load-dumping position as the skip passesi ove her n oa in tati n; ai yca ero0 ee-.- ing fashioned to gradually tilt the skip body-from. load-carrying; to its maximum. load-dumping-pfl- Sui-01111 130 cause the. material tovgradually. discharge; therefrom; and cammeans adjacent said. skip'roller for'engaging-saidguide roller forcausing said skip; roller to fol1owin= a predetermined path through .the segments. ofsaidcam. to cause the=skip to assumemaximum dumping-position with aeminimum, of cam width and permitting; said skip to overrun its maximum. dumping pps i-.

tipn;:without damage to-it. or to -.adjacent.str.ucj-.-

tunes.-

2.: a. skip; installation for; an open pit mi ne,: anrinclinedtracklying against .the walls of said. pit-andmaui-ngpne end terminating, adj acentqthe bottom; of-said pit;,a loa,ding station at,the lower endof said-track; a controltower above-the pit, for supporting ;the upper end of thetrack; a. receiving hopper in the control tower, a. skip, com-. prising.- a rectangularly shaped open frame, wheelson eachcornenof said frameadapted for traveling. movement on. said-..tr ack,- aloacl carrying body; saidskip body being substantially. rec; tangularly shaped and havinggabottom, rear and two opposed sidewalls and an. open front; and top, saidbody being pivotallymounted within said frame with its pivotalaxis onsaid side :walls and extending transversely of said frame and track a -stop carriedby the skip body at therearendthereof .engageable with a portion ofsaid wheeled frameto hold thev skip body in normal load-carrying position: at: the same inclination as said track, a pair of cam pla es adjacent-to the receiving hopper providing elongated cam surfaces, cam. engagingelementsmounted on the forward lower corners ot-the. skip. body engage: able with. said cam surfaceswhen the skip.ap-.. proachesv the unloadingstation, said cam surfaces being elongated and; shallow whereby said elements-remain in engagement therewith duringall of the period when saidbodyisout of. normal load-carrying position andwherebysaid cam elements. and canr-surfaceswill eifect a gradual and positive load-.dumpingaction to theskip body as it passes overthereceivinghopper;

3. In an apparatusiof. the class. described, an inclined-track:havingone end-terminating irrthe bottom of apit-oropen mine, a loading stationatsthelowerend of said track, acontrol'tower, above thepit .for supporting the .upper end .of the track,,a.receiving hopper in the control tower,v a skip comprising a rectangular, frame. said frame. havinga pair of transverse axles, oneat the forward and one at the rear end thereof, a wheelateachendof each of said axles adapted for traveling movement on ,said;track,' a load carrying body i pivotally imounted 'Oll said" frame with .its .pivotal axis extending transversely of said'body between said axles, means carried by the skip .body..engageable. with means on the wheeledjrame to. hold the skipbody in 'load5 carrying .position substantially parallel with said; track,,a pair of cam plates. mounted adjacent said tracks andto the receiving hopper provid ing inwardly facing longitudinally. extendingcam grooves which are. elongated. longitudinally of saidjtrack, but: are relativelygshallow in their curvature, means. forming. a recess or gap in the lowerwall'of each cam groove and dividingsaid,

grooves into two opposed similarly disposed parts, cam rollers mountedon the forwardfllower cornor; of.- the. skip. body;receivable-i1r saidcamgrooves. when the. skip approaches the unloading; station, a camelement'onthe skip bodyl adjacent.

to ac cem-= ler-' neaeea l zwi -s pair? of rollers mountedabove; the; reeessesion gapg in; the bottom .of; said longitudinally; extending cam grooves;thereby to. g uide;tl 1e cam rollers into-said depression -to; impart a positiveand -uninte '1uipt eel-tilting movement to'the-,sldp body which is; constant as it passes fromone-partinto; the-other.- ofv saidgrooves whereby its' load :is dischargede from; the skip with; minimum impact" 2': kin ns a lati n. c ord n e==c 3,. wherein dual skipsgaremtilized:for-operatiomon spaced tracks, and power means is provided for alternately moving said skips up and down on said -tracks,- wherebyythe; weight of the: empty descending skip counter-balances a portion of the weight ,of the ascending loaded skip;

5. In a skipinstallation for running-on the inclined walls of an open pit mine; asubstantiallyuniformly inclined track mounted'on said walls; atloading; station atlthe lower endof saidtrack: atower at the upper end of said track for sup:- portingthe upper end of said track; a receiving hopper insaid tower providing an unloadingstmv tion; a skip. comprisinga rectangular openframe; wheels mounted'at each corner'of said frame to. carry said frame along said track and maintainsame at all times at the same inclination assaid track; means for propelling said skip along. said track; a substantiallyrectangular skipbodyhaving a bottom, rear, and two-opposed side' walls; pivotal mounting-means-on-each of-Vsaid side walls for pivotally supporting said; body within said. open frame; means on said bodyengaging said frameto normally hold said bottom wall in substantially parallel-relation-to saidinclined track except when saidbody is beingdumped; and means adjacent said track at said unloadingstation for tipping saidqbody to unload same through its open forward end,

6. The structure as set forth in claim '5' and: said tipping means, comprising: a pairof cam plates:mountedadjacent saidtracks providing elongated cam: grooves extending longitudinally of saidtrack; said grooves being in two segments; said segments being in end to end relationship j and curved upwardly and" away from eachother from their-meeting point; cam rollers mounted r on the'forward lower cornersof said skipbody; andreoeivable in said cam grooves; and means to guide said cam rollers from one ofv said segments into theother whereby movement of said framer along-saidtrack over saidcam plates will cause said body to tilt and discharge its load.

LEWIS CL ERICKSON.

References Cited in the file of this patent UNITED .STATESzPA'I'ENTS.

Number. Name Date 903,263 Angove Nov'. 10, -1908- 985,398. Cook Feb. 28-,- 1911- 1,026,988 Lawton May 21,- 1912 1,394,915. Lohr. Oct. 25, 1921 1,446,313. Mel1in= Feb. 20, 1923. 1,542,914.. Shanaberger June 23,1925, 1,567,522. Lepley- Dec/29,. 1925. 1,712,495 Farrell May 14,1929 1,966,390 Hick July 10, 1934 1,993,081 Anderson Mar; 5,1935 2,443,546 Weggum June..l5, 194s.

FOREIGN. PATENTS Number Country Date- 1876/26--- Australia May :17, 1926' 

